User Review: Marmot Women's Trestles 15

I live in New Zealand, and have used a Marmot Trestles 15 for the past 3 years. It's my first really good sleeping bag, so I don't have much to compare it to. 

It's been a really good bag, good for using inside the huts, where it's quite warm. But I usually prefer to sleep outside, using a bivvy bag. In freezing conditions, in Trestles 15 and bivvy bag, I am only warm enough if I have piles of clothes on as well, and then I have to huddle in a kind of foetal position. I am female, and a very cold sleeper. 

I like my Trestles bag,  it is very good quality but I am soon going to try a down bag.